Tracey Emin: 20 Years Scottish National Gallery of Modern Art, until 9 Nov

Richard Hamilton: Protest Pictures Inverleith House, until 12 Oct

Sanford Wurmfeld: E-Cyclorama Edinburgh College of Art, until 5 Sept

Janet Cardiff and George Bures MillerFruitmarket Gallery, until 28 Sept

Tracey Emin: 20 Years is an assault of a show. There is no escape from the agony. The corridors are lined with images of abuse, betrayal, sickness and abortion, tales from hell retold in embroidered banners and neon. The galleries are crammed with martyr's relics: hospital tags, bloody plasters, painkillers, failed contraceptives, the famous bed with its stained knickers and stubbed fags - supporting evidence to further jeremiads in prose and video. The soundtracks bleeding from one room to the next alone would make you scream, except that Emin does it for you: at the top of her lungs and naked in Norway, in homage to Edvard Munch.

It has to be a joke, this video, doesn't it? Emin couldn't possibly expect us to take this absurd literalism seriously - or could she? This is a question for any visitor to her retrospective. Go round it solemnly by all means (and I never saw so much respectfulness as in Edinburgh), but every now and again ask yourself whether Emin mightn't actually be sending herself up.

In the space of six days in 1995, for instance, she endures a hangover, diarrhoea, vomiting, chin scabs, an abscessed tooth, a lung scan, the removal of the tooth and the fitting of an IUD, all documented in a written account accompanied, alas, by assorted forensic items. And what does Emin call this display of self-pity, this melodramatic inflation of her own averagely awful suffering? She jacks it up to The Week From Hell.

A school skiing trip as a teenager is so traumatic Emin wets the bed, and in embroidering her tale of the ordeal incorporates a Turin Shroud of a sheet as if she had preserved the original; which, incidentally, is exactly what credulous admirers like to believe, claiming it still smells of urine. Yet the sheer scale of the stain is surely some kind of self-parody.

Doesn't the fragment of overheard speech at the bottom of another embroidery, Super Drunk Bitch - 'I have to get Tracey home' - appear like a punchline? And isn't the recriminatory accusation You Forgot to Kiss My Soul a neat satire of her chronic self-pity, especially when written up in Barbie-pink neon?

There is an alternative argument - and this is the standard praise of Emin - that she is one of the great tragediennes of our time, that she bears our grief for us, does our bedwetting for us, expresses life's anguish like no other contemporary artist.

But almost everything in this show goes against those claims. For 20 years, it seems, Emin's art has been exclusively preoccupied with Emin, and demands that you be just as interested too: in her Margate childhood, her Turkish dad and English mum, in her abortions and broken affairs, her feelings about babies and cats, in the sheer authenticity of her emotions.

It is true that she sometimes crystallises the universal condition of self-pity in bright neon - 'It is fucking agony, and I'm alone!' - but Emin is no Munch, coining indelible metaphors of anguish. Nothing is expressed beyond what is stated. And what is stated often sounds so implausible - the lover so jealous he had the windows barred, the abortion where the fetus trickles down her leg - that Emin's authenticity comes into question. Are these lies or exaggerations?

If midlife has brought contentment then Emin doesn't show it; she can always return to past horrors and frequently does. In fact, it is hard to see what has changed in all these years. The art still relies heavily on Munch and Louise Bourgeois, with traces of Klee, and the song remains the same: self-pitying, outraged, sentimental, as she herself surely, and humorously, acknowledges.

If Emin is the celebrity of the Art Festival, Richard Hamilton is the grandee. The founding father of Pop Art has a show of protest paintings at Inverleith House. You might argue that he has never produced anything else, but these works are specifically political, from Hugh Gaitskell mutating into a monster in the era of nuclear proliferation to Tony Blair as an all-American cowboy in Iraq.

A whole room full of variations on Swinging London - that back-window shot of Mick Jagger and the art dealer Robert Fraser being driven away after a draconian sentence for drugs, the flashbulb flaring on their handcuffs - shows how eloquent Pop could be. Collaged, overprinted, fitted with real metal cuffs, smeared like newsprint, blurry as a black-and-white telly, the series has become more redolent of the period than the original photograph.

It is good to see Hamilton's Treatment Room, a walk-in operating theatre where Margaret Thatcher is administering her own brand of medicine from a video above the operating table in which you are the helpless patient. And it is good to see a poster for his ICA show protesting against conditions in the Maze in the 1980s. Hamilton may have missed the target with Blair but he has been a rare redemptive force in recent British art.

At Edinburgh College of Art is Sanford Wurmfeld's oval cyclorama, a vast surround-sound painting made up of fractional variations in the spectrum. Colour appears to change before your very eyes; a fine line of green turns orange at some point you cannot determine. The room swoons and light glows and fades within the painting itself. There is probably a formula of hue, tone, proportion and density to explain these phenomena, but the effects are beautiful beyond science.

The talk of the town, though, and the best contemporary art in Edinburgh this festival, comes from the Canadian artists Janet Cardiff and George Bures Miller. They have six installations at the Fruitmarket Gallery, all strikingly original in their way - the house of books, spines out, a library turned in on itself which transports you a thousand times over through the titles alone; a mechanical ballet over which the viewer has sinister control; a miniature cinema which revolves entirely around you.

Most stunning of all is Opera for a Small Room, performed in an eerie shack reached through visible darkness. Inside, among dusty bric-a-brac and walls lined with LPs, eight turntables and a dozen old lights become an orchestra for a dark and shattering tale of disaster. An old radio mic gives out the story, howling like a wolf, weeping, remembering, possibly lying, as the music crosses, merges and swells. It is a thriller in which the sound of a train plays a crucial part. It is an opera without any singers. It is Cardiff and Miller's masterpiece. It is also, as it seems to me, a complete history of music in 20 minutes, as well as a testimony to sound as illusion and to the shocking power of silence.